A plasma display panel is classified as an AC or DC type according to its driving form and classified as a surface discharge type or an opposing discharge type according to its discharge form. In terms of high definition, large screen size, facilitation of production and others, the surface discharge AC type plasma display panel has become mainstream under present conditions.
The plasma display panel has a surface panel and a back panel that are made by forming electrodes and various projections serving as barrier ribs and others on glass substrates. With the surface and back panels opposed to each other, their periphery is sealed, and their interior is filled with inert gas or discharge gas.
Referring to FIGS. 6-8, a description will be provided hereinafter of the structure of the typical surface discharge AC type plasma display panel. FIG. 6 is a perspective view of the surface discharge AC type plasma display panel. FIG. 7 is a sectional view taken along line A—A of FIG. 6, and FIG. 8 is a sectional view taken along line B—B of FIG. 6. Transparent surface substrate 1 such as a glass substrate is formed with a plurality of strip-shaped display electrodes 4 each formed of a pair of scan electrode 2 and sustain electrode 3, and light-shielding layer 5 is formed between adjacent display electrodes 4 on surface substrate 1. Scan electrode 2 and sustain electrode 3 are formed of respective transparent electrodes 2a, 3a and respective buses 2b, 3b, made of silver or the like, and which are electrically connected to respective transparent electrodes 2a, 3a. Dielectric layer 6 is formed above surface substrate 1 to cover display electrodes 4 and is covered with MgO film 7 functioning as a protective film as well as a secondary-electron-emitting film. Front panel 20 is thus formed of these elements.
Back substrate 8 disposed to face surface substrate 1 is formed with a plurality of stripe-shaped data electrodes 10 in a direction orthogonal to display electrodes 4 each formed of scan and sustain electrodes 2, 3. These data electrodes 10 are covered with dielectric layer 9. A plurality of stripe-shaped barrier ribs 11 is arranged parallel to data electrodes 10 on dielectric layer 9, and each barrier rib 11 is located between data electrodes 10. Phosphor layer 12 is provided between adjacent barrier ribs 11, covering a side of each barrier rib 11 and dielectric layer 9. Back panel 30 is thus formed of these elements.
Front and back panels 20, 30 are opposed to each other across a minute discharge space with scan and sustain electrodes 2, 3 orthogonal to data electrodes 10, and their periphery is sealed. The discharge space is filled with a discharge gas such as helium, neon, argon, xenon or a gas mixture. Barrier ribs 11 partition the discharge space into a plurality of sections, so that discharge cells 13 are formed at intersections of display electrodes 4 and data electrodes 10.
A write discharge is first caused between display electrode 4 and data electrode 10 in discharge cell 13 selected from the plurality of discharge cells 13 by data electrode 10. Thereafter, a main discharge is caused between scan electrode 2 and sustain electrode 3, whereby vacuum ultraviolet rays are generated. The vacuum ultraviolet rays strike phosphor layer 12, thereby being converted into visible light. In this way, the plasma display panel performs display.
Phosphor layers 12 having respective colors of red (R), green (G) and blue (B) are successively deposited in adjacent discharge cells 13, respectively. Light-shielding layer 5 covers between discharge cells 13 to shield the light coming from adjacent discharge cell 13.
To meet a demand for higher image quality, the plasma display panel has increasingly high definition. In the high-definition plasma display panel, the number of pixels or discharge cells 13 increases per unit area of a display screen. With the size of the screen remaining the same, the area of each pixel or discharge cell 13 reduces, so that the surface area of the phosphor layer exposed to the vacuum ultraviolet rays reduces. Consequently, the panel has reduced luminance.
As examples for improving the luminance of the panel, an example of providing a projection shorter than the barrier rib in the discharge cell and coating this projection with a phosphor for increased surface area of the phosphor layer, and an example of providing a recessed and projected part at the barrier rib or the dielectric layer that is to be coated with the phosphor for increased surface area of the phosphor layer are disclosed in Japanese Patent Unexamined Publication Nos. 2000-77002, 2001-273854 and 2002-8544.
However, the above-described example of providing the projection shorter than the barrier rib in the discharge cell or providing the recessed and projected part at the surface of the barrier rib or the dielectric layer requires a complicated process of forming the projection or the recessed and projected part particularly in the extremely minute discharge cell. Moreover, the projection or the recessed and projected part reduces the volume of the discharge space, thus adversely affecting the discharge.
In view of the problems described above, the present invention aims to realize a plasma display panel with improved luminance and a method of manufacturing this plasma display panel. The present invention can increase the surface area of a phosphor layer without reducing the volume of a discharge cell of even the high-definition plasma display panel.